Speeding up of microstructure reconstruction: I. Application to labyrinth patterns

Recently, entropic descriptors based the Monte Carlo hybrid reconstruction of the microstructure of a binary/greyscale pattern has been proposed (Piasecki 2011 Proc. R. Soc. A 467 806). We try to speed up this method applied in this instance to the reconstruction of a binary labyrinth target. Instead of a random configuration, we propose to start with a suitable synthetic pattern created by cellular automaton. The occurrence of the characteristic attributes of the target is the key factor for reducing the computational cost that can be measured by the total number of MC steps required. For the same set of basic parameters, we investigated the following simulation scenarios: the biased/random alternately mixed #2m approach, the strictly biased #2b and the random/partially biased #2rp one. The series of 25 runs were performed for each scenario. To maintain comparable accuracy of the reconstructions, during the final stages the only selection procedure we used was the biased one. This allowed us to make the consistent comparison of the first three scenarios. The purely random #2r approach of low efficiency was included only for completeness of the approaches. Finally, for the conditions established, the best single reconstruction and the best average tolerance value among all the scenarios were given by the mixed #2m method, which was also the fastest one. The slightly slower the alternative #2b and #2rp variants provided comparable but less satisfactory results.Comment: 11 pages, 3 figures, 2 tables, published versio

The influence of mechanical damaging on positrons lifetime in ultra-high-molecular polyethylene

The influence of damaging of the ultra-high-molecular polyethylene (PE-UHMW) Chirulen ®1120, which is applied, among others, to produce hip endoprostheses, on spectra of positrons lifetime in this material was investigated. Polyethylene samples were damaged by: impact, rolling friction and collisions with metal balls in a planetary mill. Changes in the parameters of positrons lifetime spectra related to annihilation of ortho-positronium (o-Ps) were analyzed in dependence on the mechanical energy passed to the sample. On the basis of the Eldrup–Tao model, changes in the radii of voids in which a positronium is formed and annihilated, as well as changes in the degree of filling up the space atoms in the examined polymer were determined.Досліджували вплив пошкоджень ультрависокомолекулярного поліетилену марки Chirulen®1120, який застосовують для виготовлення тазостегнових ендопротезів, на час існування позитронів в цьому матеріалі після опромінення. Зразки поліетилену пошкоджували в лабораторних умовах методами удару, вальцювання та тертя, а також шляхом зіткнення з металевими кульками у планетарному млині. Зміни часу існування орто-позитронів аналізували залежно від механічної енергії, отриманої зразком, а зміни радіусів порожнин, в яких утворюються та анігілюються позитрони, визначали, застосовуючи модель Елдрупа–Тао.Исследовали влияние повреждений ультравысокомолекулярного полиэтилена марки Chirulen®1120, который применяют для изготовления тазобедренных эндопротезов, на время существования позитронов в этом материале после облучения. Образцы полиэтилена были повреждены в лабораторных условиях методами удара, прокатывания и трения, а также путем столкновения с металлическими шариками в планетарной мельнице. Изменения времени существования орто-позитронов анализировали в зависимости от механической энергии, полученной образцом, а изменения радиусов полостей, в которых образуются и аннигилируются позитроны, определяли с применением модели Елдрупа–Тао